1. Field of the Invention
Embodiments of the present invention relate, in general, to wireless hierarchical networks and particularly to hierarchical wireless regional area network networks using frame transmissions pipelining.
2. Relevant Background
The 802.22 wireless regional area network (“WRAN”) system is aimed at providing broadband access with capabilities similar to the asymmetric digital subscriber line (“ADSL”) and cable modem technologies over less populated rural areas. The typical range of such a system is limited based on transmitting power of a base station.
As is known to one skilled in the relevant art, a 802.22 system constitutes an 802.22 Media (or medium) Access Control (“MAC”) and physical implementation in which at least one subscriber station communicates with a base station via a point-to-multipoint (P-MP) radio air interface. Services associated with such a communication are supported by the MAC and physical protocol layers. Typically radio communications within the above range can be possible in near- and non-line-of-sight situations between a base station and a subscriber station, also known as a customer premise equipment terminal. This line of sight operations however may include partial and even complete blockage by foliage or other obstacles which will in many situations contribute to signal attenuation and multi-path effects. Deployment configurations of 802.22 networks also include the optional use of macro diversity, i.e. optimization through the use of repeaters or relay stations.
An 802.22 system generally consists of one base station radio and one or more Consumer Premise Equipment (“CPE”) radios. In such a system the base station (“BS”) is radiating its downstream signal (forward) toward the CPE's with a variety of antenna configurations including omni-directional, a shaped sector or optionally an adaptive array (spatial reuse) antenna, each attempting to achieve broad beam width to azimuthally “cover” a number of prospective subscribers.
Repeater stations augment the coverage of a WRAN by extending the base station's reach. Current relay stations simply pass on, or repeat the signal by acting as a dedicated signal repeater. This repeating can lead to self-interference of signals and excessive bandwidth utilization. Self-interference from the use of repeaters occurs since they typically use the same channels used by the BS and the CPE terminals. In general, there is an interference-throughput tradeoff resulting from the use of repeaters since self-interference would typically result in lower throughput. In addition, simply repeating a signal in an attempt to extend the coverage of one or more BSs increases transmission transition overhead. Repeater stations are also unable to effectuate handoffs between one BS and another in the event of a communication disruption. This disruption can be caused by a wireless microphone or TV broadcast.